Modifying a 45ACP cylinder?

[MikeS]

Hi All.

I have a Cimmaron Thunderer that was 44 Special that I had rebarreled to 45, and have both a 45LC cylinder, and a 45ACP cylinder for it. When they chambered the 45ACP cylinder they cut it in such a way that 45 Auto Rim cartridges won't fit. Would it simply be a matter of cutting off some of the rear of the cylinder so that 45AR cartridges could fit? As it is now when putting 45ACP cartridges into the cylinder they go in so that the rim is partially in the cylinder (giving the case the most support), if it was cut back some so that more of the rear of the case was exposed that shouldn't be a problem as the 45ACP headspaces off the mouth of the case, and that wouldn't change, is that correct? Cutting the cylinder back enough to fit an AR case shouldn't expose the ACP cases to the point that any of the sidewalls of the case (other than the solid web) would be exposed, would it?

I'm kind of disappointed, as I really thought I would be able to shoot AR cases out of the ACP cylinder, but I didn't tell the gunsmith doing the work that I was planning on using AR cases, so I can't blame him that they don't work. It's not really that big of a deal if I can't shoot AR cases in the gun, I just wanted to be able to, so I could load some revolver only loads and have no way of accidentally loading them in my 1911.

[jethunter]

.45autorim is meant to use as replacement for .45acp used with moon-clips. IMO machining down the rear of the cylinder (a la webley MKI/II) is workable ONLY if you were planning on using .45acp in moon-clips from then on. Stand-alone .45acp isn't going to work after you modify the cylinder for .45autorim.

If you trim the rear of the cylinder enough to accept .45autorim, it would leave portions of BOTH the .45acp and .45autorim cases unsupported immediately forwrd of the head/rim, since the .45ar case would also end up headspacing on the neck just like your .45acp does now. To fix that you would need to ream the chamber slightly longer. BUT doing this is going to give you too much gap between the rear of the cylinder and the frame to use with a .45acp unless you are using it with moon-clips.

Bottom line is you need to decide if you wnat to use .45autorim/.45acp with moon clips, OR .45 acp . Hope that makes sense.

[Nueces]

I must respectfully disagree with the gentleman from Alberta. MikeS's revolver is a Colt style single action, and can't be used with moon clips.

MikeS, your proposal is entirely workable. DA revolvers cut for 45 ACP and clips are all relieved at the rear end as you propose. The case heads are supported as designed, to accommodate the clips, with both ACP and AR cases supported for the same body length. A revolver originally chambered for the 45 ACP without using clips will have a chamber that headspaces the case on the mouth.

Shortening your cylinder from the rear will give you the same geometry as found in a DA revolver. No chamber deepening will be required. The ACP cases will continue to headspace on the mouths, as designed, and the ARs on the rims. Will make a neat handgun.

Mark

[Harter66]

I agree w/Nueses on this. There is also the possibility of shooting the adopted unofficial"45 special" ,a Colts case shortened to ACP length. It has a thinner rim than the AR.

Jethunter,

The AR case has a rim thickened to take up the typical depth of the ACP rim and the moon clip thikness and I belive is intended to head space on either the rim, mouth or both. The proper cut on the cylinder would most likely not expose even the whole extractor groove in current ACP cases. Based only on some fooling around w/a Colt 1917.

[jethunter]

I must respectfully disagree with the gentleman from Alberta. MikeS's revolver is a Colt style single action, and can't be used with moon clips.

MikeS, your proposal is entirely workable. DA revolvers cut for 45 ACP and clips are all relieved at the rear end as you propose. The case heads are supported as designed, to accommodate the clips, with both ACP and AR cases supported for the same body length. A revolver originally chambered for the 45 ACP without using clips will have a chamber that headspaces the case on the mouth.

Shortening your cylinder from the rear will give you the same geometry as found in a DA revolver. No chamber deepening will be required. The ACP cases will continue to headspace on the mouths, as designed, and the ARs on the rims. Will make a neat handgun.

Mark


I agree that moon clips can't be used in a SA, I was trying to say that the ar case is made to be interchangeable with acp cases used with moon clips.

I have seen and shot one of these single cylinder / dual cartridge conversions and was not pleased with the bulge on the acp case. Maybe I am too picky.

[35remington]

jethunter, your comments are not relevant to this particular pistol. No case bulging would occur should this pistol be altered. The capability to use 45 ACP and Auto Rim would remain.

Your concerns are unfounded.

[x101airborne]

I had the same issue of not wanting to accidentally exchange loads meant for a revolver in my autos. I simply use a 240 gr SWC for my revolver only loads and nickle cases. For my autos, I am using Miha's EXCELLENT 200gr HP in brass cases. My auto wont feed the SWC due to overall length too long for the mag and the wide shoulder of the swc creates a cartrige too long for the autos. Those conditions coupled with the easily identifiable cases and boolit designs pretty much give me a warm fuzzy about being able to keep my ammo separated. Even if one did accidentally get swapped over, I guess not much would happen because I am only .3 grains over what the Lee book says is good to go. I know I will get flamed for it, but the accuracy was not there without the .3 grains. I tried it several times and even tried to re-alloy my melt to get away from the extra .3 grains. Just wouldn't happen, so here I am. I am still comfortable with my results. BTW.... Im using Herco.

[jethunter]

I don't doubt you but I have not entirely bought into the idea yet. I'm not trying to be stubborn, although some people have called me that.

Help me understand why the example I saw bulged the acp cases? Too much cylinder removed?

[35remington]

Look again at an Auto Rim case and ACP case, side by side.

You'll notice the rim on the Auto Rim is not as thick as the extractor groove cut. No exposed case wall results in altering the cylinder when ACP cases are used in the revolver cut for the Auto Rim. The cartridge is well supported either way. The only little bit sticking out of the cylinder when an ACP is used in an Auto Rim chamber is extractor groove, not case wall.

Keep in mind how a single action revolver extracts. No ejector star. However, it's not a problem with a DA revolver either in terms of case wall support.

If you saw bulged cases, you also saw an incompetent hack job that was passed off as gunsmithing.

Bad example. Not typical of work anyone that wants repeat business would do. Put that out of your mind.

An ACP case fired in a revolver with an Auto Rim chamber has better case wall support than an automatic pistol does.....even when the case slams back against the recoil shield under firing pressures. Only part of the extractor groove is exposed, and that's not a weakness.

I like Herco in the Auto Rim and ACP myself. Great reasonably slowish burning non spiky powder. Good choice.

[theperfessor]

jethunter, there could be several reasons why you saw what you saw, and I don't doubt your observation. The chamber could have been cut oversize using the wrong reamer, or it could have been a .45 Long Colts chambered cylinder with the back face of the cylinder cut off enough to use AR cases.

I can tell you that in my 625 S&W I can use ACP cases with or without moon clips and AR cases interchangeably. There is no noticeable bulging of cases with any safe and reasonable load.

One of these days I'd like to get a .45 Blackhawk w/a .45 ACP cylinder and face the back off so I can use AR rounds with roll crimps in it. The case would still be firmly supported to a point below the bottom of the case's combustion chamber. I see no reason why that would cause a radial bulge.

[Harter66]

Jet ,
The buldged cases were most likely the result of cylinder dimensions and not of the modification. As I suggested above the modification should not expose more of the ACP case than to the top of the extractor groove. A case can only bulge if you have presure w/o a chamber wall close enough. Example your moonclip conversion was done on a cylinder cut for 45 Colts and was cut to the full .484" plus tolerance and your ammo was minimum dia at .473" that would leave a visable bulge especially if it were all on 1 side.

[Rusty W]

I have a convertible 45colt/ACP Ruger Blackhawk with the ACP cylinder cut so it will chamber the AR. I was on a mission for a 625, bought about 500 pcs of AR brass before I even found a 625. I searched for a 625 for about 3-4 months. I waited untill the Tulsa Gunshow came around thinking surely I'd find the treasure there. Nope. Went down the road a few blocks to a gunshop and low & behold there it was. $545 & tax later I was on my way home w/my new toy. Shot it for a few months & although I really wanted to like this gun, I just couldn't. Didn't like the grip, couldn't get used to the way it pointed. I took it back to the Tulsa Gunshow & got my money back the following spring. I let 200 pcs of brass go w/the gun but had about 300 pcs loaded. Didn't want to let my handloads go w/the gun so I hung on to them. I was reading an article in Handloader magazine about cutting the cyl. on the blackhawk to chamber the AR so I had mine done by a local gunsmith. The Blackhawk shoots great w/either the ACP or AR or Colt.

[jethunter]

I had to get both cases out and look at them SxS as was suggested. I had the idea that the ar case was longer by the length of the rim, but too my surprise they are the same length. My mistake.

I'm off to a great start, 2nd post and already stuck my foot in my mouth. Sorry.

[leadman]

jethunter, we all do it on occasion. Wish my feet we smaller though!

The good part is you are of an open mind and discussed it civily. We all learn we we are like that.

[GabbyM]

Some of the race gun crown will bevel out the cylinders for speed loading. They want to be able to throw that loaded moon clip at the cylinder and have it fall in. When jethunter was seeing bulged cases I'd have to look at the cylinder mouths first for this type modification. Would want to look for it on a used 625 also because I'd not want it on mine.

You get this similar situation on a 1911 after someone gets carried away with there Dremel tool grinding a "feed ramp" in the barrel.

[Char-Gar]

It is entirely possible and feasible to modify a single action pistol's 45 ACP cylinder to take the Auto Rim case and still use the ACP case with safety and reliability. It is done quite frequently. I have done it myself on several occasion. I am surprised at the debate over this.

Now how you do it is another issue. On larger cylinders like the Ruger Blackhawk, all that is necessary is to turn enough metal off the back of the cylinder to allow for the thicker rim of the AR case.

When you go to smaller cylinders things can get a little more complex. On the New Vaquero cylinder the AR rim would fit into the scallops on the ratchet and to turn down enough steel you would have to turn off part of the ratchet. The solution to this is to pocket mill the back of the cylinder to allow the thicker AR rims.

[Nueces]

I had to get both cases out and look at them SxS as was suggested. I had the idea that the ar case was longer by the length of the rim, but too my surprise they are the same length. My mistake.

I'm off to a great start, 2nd post and already stuck my foot in my mouth. Sorry.

The impression that's going to stick comes from seeing that you checked your premises, changed your thinking and got back on here to say so. Nicely done and welcome aboard!

Mark

[Bob Krack]

The impression that's going to stick comes from seeing that you checked your premises, changed your thinking and got back on here to say so. Nicely done and welcome aboard!

MarkMy sentiments exactly Mark, welcome aboard jethunter.

Many will remember you just by your admitting your mistake.

Proud to have you here.

Bob

[MikeS]

So even the convertible RBH cylinders won't chamber 45AR cases without modification? I had thought that any revolver that could use the ACP could also use the AR cases. If this is the case, then I won't bother modifying the cylinder, and just use ACP cases only.

Ok, so now I'm off to the S&S forum to sell 100 rounds of 45AR loaded in virgin Starline brass with 3.5gr & 4.2gr (50 of one, 50 of the other) of Trail Boss under a 452423, and a couple of Lee shell holders, one for a press, one for a Lee priming tool. Now that I think of it, I have no clue what they're worth! Anyone have any idea what a fair price would be?

[Uncle R.]

Ok, so now I'm off to the S&S forum to sell 100 rounds of 45AR loaded in virgin Starline brass with 3.5gr & 4.2gr (50 of one, 50 of the other) of Trail Boss under a 452423, and a couple of Lee shell holders, one for a press, one for a Lee priming tool. Now that I think of it, I have no clue what they're worth! Anyone have any idea what a fair price would be?

I suggest you pull 'em down and sell the primed cases instead. My personal rule is to NEVER sell handloaded ammo - not for five bucks apiece - not for any price. Give it some thought - there are lots of threads here about the hazards and risks of selling handloads.
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Uncle R.

[Tatume]

.45autorim is meant to use as replacement for .45acp used with moon-clips. IMO machining down the rear of the cylinder (a la webley MKI/II)
[...]
I have seen and shot one of these single cylinder / dual cartridge conversions and was not pleased with the bulge on the acp case. Maybe I am too picky.

It is very common for Webley revolvers of the various marks to exhibit bulged or split cases when converted to 45 ACP or AR. The nominal base diameter of the 455 Webley cartridge is 0.480" and the 45 ACP base is nominally 0.476". But the chambers for the Webley revolver are often cut considerably oversized, for an already larger cartridge case.

Take care, Tom

[Moonie]

A closed mouth gathers no foot. It isn't the fact that you inserted it, it's the fact that you were willing to admit you were wrong. Too many are unwilling to do the latter.

[The Virginian]

For the altered Webleys what you need to do is fire the virgin brass once with your reduced .45 ACP or .45 Auto-Rim load, then after cleaning the fired cases use a .455 Webley/Eley sizng die or even a .45 Colt die since the cases were undersized for the first firing. Load the cases as normal from that point on using the 455 die set. Mark your boxes for use in a converted .455 as the rounds won't chamber in a 45 ACP/AR revolver after that.